Would humanoids and the like become outsiders when they travel to another plane, and if not, then why do all of the other planes only contain outsiders, and not material-plane equivalents?
Example: A Hell Hound is obviously a completely different creature than a Babau, but they are both simply lumped together as 'outsiders', so far as I know only because they are not of the material plane. So, when on their home plane, why are they not considered separate species, such as Dragons and Humans, when they are easily as different from one-another?